System for detecting defective battery packs

ABSTRACT

An electrical cabinet for an uninterruptibe power supply (UPS) system includes universal slots that can receive power modules, battery packs, or chargers. The back plane of the slot has connector terminals for battery packs and power modules. The cabinet can be easily reconfigured as desired by changing the number of power modules chargers or battery packs installed. Circuitry is provided that indicates the capacity and operational readiness of the cabinet. This circuitry monitors the battery packs in each slot, and isolates any detected fault to a particular pack.

FIELD OF THE INVENTION

[0001] The present invention relates generally to modularuninterruptible power supply (UPS) systems, and more particularlyrelates to battery monitoring systems for use in such UPS systems.

BACKGROUND OF THE INVENTION

[0002] Increasingly, businesses, hospitals, utilities, and evenconsumers are relying on electronic and computerized equipment toconduct their daily activities. Indeed, as we progress through the neweconomy in the information age, the amount of reliance and the requiredsophistication of the electonic equipment used will only increase.Unfortunately, such increased use and sophistication of teh electronicequipment brings an increased demand for reliable, quality electricpower without which operations may be disrupted and critical data lost.

[0003] Despite the advances in the sophistication and availability ofelectronic and computerized equipment, the availability and reliabilityof high quality electric power and the quantities demanded by thegrowing economy has not kept pace. Indeed, while many utilities believethat rolling brown-outs provide an adequate solution to their inabilityto supply the electric power required by their customers, the impactthat such brown-outs has on a business' productivity and profitabilityis, quite simply, unacceptable.

[0004] In addition to the utilities' inability to reliably supply theamount of electric power required, the quality of the power that issupplied often is so poor so as to affect the operation of the modernsophisticated electronic and computer equipment. Voltage sags and spikesare relatively common on the utility power lines, particularly duringperiods of factory shift changes in industrialized areas. Other powerquality problems may be introduced by natural causes such as lightninginduced voltage spikes, voltage droops carsed by accidental contact withpower distribution equipment by animals, tree limbs, etc. Oftentimes,these power quality perturbations have a more detrimental effect on theelectronic and computerized equipment than complete power losses becausethe operating characteristics of the components of such equipmentvaries. That is, some portions of the electronic equipmnet may ceaseoperating before other portions shut down, possibly resulting inerroneous operation, corrupted data, etc.

[0005] To overcome these and other problems resulting from the lack ofthe quantity and quality of electric power required by the modernelectronic and computerized equipment, uninterruptible power supplysystems have been developed. These systems typically allow the mainutility power to supply the connected load during periods ofavailability of high quality utility generated electric power. However,during periods of utility power loss or substandard quality, thesesystems will stop utilizing the utility power input and switch to analternate source of electric power to generate the required output forthe connected loads. Most often, this alternate source of electric poweris from a number of electric storage batteries. Even in systems that mayutilize a motor-driven electric power generator, batteries are stilltypically utilized to bridge the gap between the loss of utility powerand the availability of the motor-driven generator, which typicallyrequires a finite period of time after it is started before it iscapable of powering the connected loads. Because the applications varygreatly in their type, size and configuration, powering requirements,signal requirements and the like, it will be readily appreciated tothose skilled in the art that one size fits all does not apply and theone size and form of an uninterruptible supply systems can not meet therequirements of all applications. Indeed, it is often the case that eachapplication requires a significantly different configuration of an UPSsystem.

[0006] The two basic components used in UPS systems include batterypacks and power modules. It is also desirable in certain applications touse battery chargers in the UPS systems. Battery packs have positive andnegative terminals which can be connected together in parallel or seriesto provide the desired combined DC voltage and amperage. Power modulesare much different than battery packs and can serve the purpose ofsignal conditioning and converting DC electrical power into ACelectrical power. Because power modules are typical controlled throughelectronic control signals, power modules must have several inputs andseveral outputs. As such, power modules use much more complex terminalconnectors than battery packs with several input pins and several outputpins.

[0007] The electric power storage batteries used in typicaluninterruptible power supply systems are constructed from a number ofindividual battery cells that are coupled in series to generate theoutput voltage required for the system. Since each of the individualbattery cells are required to generate the proper output voltage, properoperation of each of the battery cells is paramount to the system'sability to properly supply quality output power to the connected loadsto prevent the problems discussed above. The existence of an undetectedfailed cell may result in a system crash during periods of utility poweroutage when the batteries are called upon to supply the connected load.Alternatively, the duration or quality of the output power supplied bythe system for the batteries may be greatly reduced, which is alsounacceptable from a user standpoint.

[0008] To avoid the continued existence of a failed battery cell, someform of battery health monitoring for the UPS system is required. Oncesuch monitoring system is described in a paper presented at the 13thInternational Telecommunications Energy Conference held in Kyoto, Japan,on Nov. 5-8, 1991 entitled Middle Point Voltage Comparison as a Simpleand Practical but Effective Way to Ensure Battery Systems Capacity toPerform, written by Arto Glad, Pekka Waltari, and Teuvo Suntio. Themonitoring system proposed by this paper uses a voltage signal UWD usedto represent the “middle point” voltage as determined to be the voltagedeviation between a fixed reference voltage and the “middle point”voltage of the battery string. Unfortunately, this paper concludes thatthe battery string must be discharged before “the real anomalies” can bedetected. Specifically, this paper states that the absolute health ofthe batteries can be revealed only by discharging about 70-80% or moreof the batteries' capacity. Likewise, in another paper presented at the18^(th) International Telecommunications Energy Conference on Oct. 6-10,1996, in Boston, Mass., entitled A Systems Approach to Telecom BatteryMonitoring and Control Using the Rectifier Power Plant” written by KevinE. White, also requires that the battery be discharged significantlybefore the health of the battery may be determined. Indeed, this laterpaper indicates that the float voltage provides no hint of a weakbattery, and requires that all battery testing be performed under load.

[0009] While the systems proposed in the above-identified papers maywell provide adequate monitoring of the health of the batteries, therequirement of discharging 70-80% of the batteries' capacity merely todetermine the health of the batteries carries with it significant risksthat jeopardize the uninterruptible power supply system's ability tosupply the connected load in the event of any utility power failureoccurring during or within a period of several hours after themonitoring has occurred, depending on the ability of the system torecharge the batteries to their full capacity after having beendischarged 70-80%. Further, the complexity of the circuitry required todisable or limit the utility power line input adds significantly to thecost and complexity of such a monitoring system, while reducing theoverall system reliability; a combination which is particularlytroublesome for a system that is meant to increase the reliableoperation of electronic and computer equipment.

[0010] Therefore, there is a need in the art for a monitoring systemthat is able to ensure the health and operability of the batteriesutilized in an uninterruptible power supply system without requiringthat these batteries be discharged during the monitoring operation.

BRIEF SUMMARY OF THE INVENTION

[0011] The system of the invention provides a new and improveduninterruptible power supply (UPS) system including a modular cabinet orchassis providing extensibility and reconfigurability of the UPS. Thisextensibility and reconifigurability is made possible through theprovision of common receiving locations in the cabinet or chassisadapted to receive any one of the components of which the UPS iscomprised. Specifically, each receiving location of the modular cabinetor chassis is adapted to receive power modules, battery packs, andbattery chargers. This provides maximum flexibility for the consumer whois now able to fuilly configure the UPS to his or her own particularneeds, and to fully reconfigure the UPS as his or her needs change, allwithout the necessity of purchasing separate cabinets.

[0012] In one embodiment of the invention, an electrical cabinet forconfiguring an uninterruptible power system comprises a plurality ofreceiving locations each adapted to receive either of a power module anda battery pack. In this embodiment, each receiving location includes aterminal connector that includes a power connector adapted toelectrically connect with the battery pack, and a signal connectoradapted to electrically connect with the power module. Further, eachreceiving location preferably includes two separate terminal connectorsarranged in non-interfering locations. Preferably, the signal connectorand the power connector are arranged in a single terminal connectoralong a common strip to which the power modules are adapted to connect.

[0013] The electrical cabinet of the invention flrdier comprisespartitions dividing the receiving locations into slots. A user interfaceis adapted to provide a status of each receiving location indicative ofthe use of the receiving location. This is aided in one embodiment bythe inclusion of sensing circuitry for each receiving locationindicating to the user interface the type of device positioned in thereceiving location.

[0014] In a furher embodiment of the invention, each receiving locationis adapted to receive at least two battery packs. In this embodiment,each receiving location includes a pair of terminal connectors, one foreach different battery pack. To accommodate the typical inclusion of afan in each power module, each receiving location including a ventarranged to be in close proximity to this fan.

[0015] A non-invasive method of monitoring operational readiness ofelectric power storage batteries in the uninterruptible power supply(UPS) system is also presented. The UPS system includes at least onebattery channel, each having at least two battery packs coupled inseries to supply output power to a connected load. A battery charger isalso preferably included to maintain and restore charge to the batteriesduring normal utility line operation. In this system, the methodcomprises the steps of monitoring the voltage at the midpoint betweenthe two battery packs during a quiescent state of operation of thebattery packs. This voltage is compared to a nominal value for themidpoint voltage during the quiescent state of operation, and a lack ofoperational readiness of both battery packs is indicated when thevoltage at the midpoint is less than the nominal value by apredetermined amount.

[0016] In UPS systems having a number of battery channels coupled inparallel with one another, the step of monitoring comprises the step ofmonitoring a voltage for each of the parallel coupled battery channelsat the midpoint. In such a system, the method further includes the stepsof calculating the nominal value for the midpoint voltage during thequiescent state of operation of the battery packs as the average of thevoltages monitored for each parallel coupled battery channel. A lack ofoperational readiness of a battery channel is then indicated when thevoltage at the midpoint of the battery packs for that channel is lessthan the nominal value by the predetermined amount.

[0017] In further embodiment, the method also includes the steps ofmonitoring the voltage at the midpoint during float charging of thebattery packs and comparing the voltage to a nominal value during thefloat charging. A lack of operational readiness of one of the twobattery packs may then be indicated when the voltage at the midpointvaries from this nominal value by a predetermined amount. The indicationa lack of operational readiness may identify one of the two batterypacks when the voltage at the midpoint is greater than the nominal valueby the second predetermined amount, and the other of the two when thevoltage at the midpoint is less than the nominal value by thepredetermined amount.

[0018] In UPS systems that include a number of battery channels coupledin parallel with one another, an embodiment of the present inventionmonitors the voltage for each of the parallel coupled battery channelsat the midpoint between the two battery packs during the float charging.The method then calculates the nominal value for the midpoint voltageduring the float charging of the battery packs as the average of thevoltages monitored for each parallel coupled battery channel A lack ofoperational readiness of a battery channel is then indicated when thevoltage at the midpoint of the battery packs for that channel variesfrom the nominal value by the predetermined amount. A lack ofoperational readiness of one of the two battery packs of that batterychannel may also be indicated when the voltage at the midpoint isgreater than the nominal value by the predetermined amount, and of theother of the two battery packs when the voltage at the midpoint is lessthan the nominal value by the predetermined amount.

[0019] In a further embodiment, the method also includes the steps ofmonitoring the voltage at a midpoint between the two battery packs at astate of discharge of the battery packs, and comparing this voltage to anominal value for the midpoint voltage during the state of discharge. Alack of operational readiness of one of the two battery packs may thenbe indicated when the voltage at the midpoint varies from the nominalvalue by a predetermined amount. A lack of operational readiness of oneof the two battery packs is indicated when the voltage at the midpointis less than the nominal value by the third predetermined amount, and ofa second one of the two battery packs when the voltage at the midpointis greater than the nominal value by the predetermined amount.

[0020] In UPS systems including a number of battery channels coupled inparallel with one another, a further embodiment monitors the voltage foreach of the parallel coupled battery channels at the midpoint betweenthe two battery packs during the state of discharge. In this embodiment,the method of the present invention includes the step of calculating thenominal value for the midpoint voltage during the state of discharge asthe average of the voltages monitored for each parallel coupled batterychannel A lack of operational readiness of a battery channel may then beindicated when the voltage at the midpoint of the battery packs for thatchannel varies from the nominal value by the predetermined amount. Alack of operational readiness of one of the two battery packs of thatbattery channel may be indicated when the voltage at the midpoint isless than the nominal value by the predetermined amount, and of theother of the two battery packs of that battery channel when the voltageat the midpoint is greater than the nominal value by the predeterminedamount.

[0021] In another embodiment of the present invention, a method ofdetecting and identifying a failed battery pack in an uninterruptiblepower supply (UPS) system is also presented. Preferably, the UPS systemincludes a plurality of parallel connected slots into which may becoupled battery packs, power modules, or battery chargers as determinedand configured by a user. The slots are adapted to accommodate twobattery packs and to provide a series coupling therebetween. This methodcomprises the steps of detecting a presence and type of equipmentinstalled in each slot, monitoring a voltage present at the seriescoupling between the two battery packs for each slot into which isinstalled battery packs, calculating an average midpoint voltage for allslots having battery packs installed, comparing the voltage for eachslot to the average midpoint voltage for all slots, and identifying afailed battery pack within a slot when the voltage for its associatedslot deviates from the average midpoint voltage by a predeterminedamount.

[0022] In a further embodiment, the method also includes the steps ofcomparing the voltage for each slot to a predetermined expected value,and identifying a failed battery pack within a slot when the voltage forits associated slot deviates from the predetermined expected value by apredetermined amount. Preferably, the method also includes the step ofdetermining an operating mode of the battery packs. In this embodimentthe step of comparing the voltage for each slot to a predeterminedexpected value comprises the step of comparing the voltage for each slotto an operating mode specific predetermined expected value. The step ofidentifying a failed battery pack within a slot may then include thestep of identifying a failed battery pack within a slot when the voltagefor its associated slot deviates from the operating mode specificpredetermined expected value by a predetermined amount.

[0023] A system for detecting defective battery packs in a modular,redundant uninterruptible power supply (UPS) system is also presented.As discussed, the UPS system includes a number of parallel connectedslots into which may be coupled the battery packs, power modules, orbattery chargers as determined and configured by a user. Each slot isadapted to accommodate two battery packs and to provide a seriescoupling between them. This system comprises a voltage sense circuitcoupled to each series coupling of each slot. A voltage sense selectorcircuit is coupled to each of the voltage sense circuits to selectivelyenable them. A controller is coupled to the voltage sense selectorcircuit to command the voltage sense selector circuit to enable aparticular voltage sense circuit for a particular slot. The controllerthen reads the voltage sense signal for that particular slot from thevoltage sense circuit. The controller compares the voltage sense signalfor the particular slot to a predetermined expected value. It thenidentifies an operational status of the battery packs based on thiscomparison.

[0024] Preferably, the controller reads the voltage sense signal foreach slot in which battery packs are installed, calculates an averagevoltage value, and compares the voltage sense signal for each slot tothe average voltage value to identify the operational status of thebattery packs for each slot. The controller may also read the voltagesense signal for each slot in which battery packs are installed during afloat charge mode. It then compares the voltage sense signal for eachslot to an expected voltage value for the float charge mode, andidentifies one of the battery packs in a slot as defective when thevoltage sense signal for the associated slot is less than the expectedvoltage value for the float charge mode. The other of the battery packsin a slot is identified as defective when the voltage sense signal forthe associated slot is greater than the expected voltage value for thefloat charge mode. The controller also preferably reads the voltagesense signal for each slot in which battery packs are installed during adischarge mode, compares the voltage sense signal for each slot to anexpected voltage value for the discharge mode, and identifies one of thebattery packs in a slot as defective when the voltage sense signal forthe associated slot is less than the expected voltage value for thedischarge mode. The other one of the battery packs in a slot isidentified as defective when the voltage sense signal for the associatedslot is greater than the expected voltage value for the discharge mode.

[0025] In one embodiment of the present invention, the voltage senseselector circuit comprises a shift register having a clock input and aslot select input from the controller. The shift register sequentiallygenerates a number of output enable signals in response to the clockinput and the slot select input from the controller. Each of the outputenable signals operates to turn on a switching element to connect thevoltage sense circuit to the controller. Preferably, the switchingelement is a metal oxide silicon field effect transistor (MOSFET).

[0026] In one embodiment, the electrical cabinet further comprises asupport base, support bars spaced apart in a rectangular relationshipextending vertically from the support base, side panels extendingvertically between different pairs of the four support posts, and anumber of shelves extending horizontally between the four support posts.In this embodiment, the receiving locations are defined between theadjacent shelves. The cabinet further includes a back panel associatedwith the receiving locations. The back panel extends generallyperpendicular to the shelves and transversely between the side panelsand two of the support bars, supporting the terminal connectors.Preferably, the shelves, the side panels, and the support bars aremanufactured from sheet metal material. Pairs of the support bars arefurther connected and maintained in spaced relation by a web of sheetmetal material.

[0027] In an alternate embodiment, an electrical cabinet for configuringan uninterruptible power system with battery packs and modules comprisesa support housing and a number of universal bays defined in the supporthousing and sized to receive either of a battery pack and a powermodule. The electrical cabinet further includes a terminal connector foreach universal bay comprising a power connector adapted to electricallyconnect with the battery pack and a signal connector adapted toelectrically connect with the power module. Preferably, each universalbay includes two terminal connectors arranged in non-interferinglocations. The housing further defines a guide surface for eachuniversal bay. This guide surface is adapted to guide the battery packinto electrical connection with the power connector and the power moduleinto electrical connection with the signal connector. Preferably, eachof the signal and power connectors also include a guide mechanism thatinteracts with a corresponding guide mechanism on either of the batterypack and power module. The guide surface is adapted to first locate thecorresponding guide mechanisms for interaction, and then guide thebattery packs and power modules into electrical connection with thepower connectors and signal connectors, respectively.

[0028] In one embodiment, the signal connector and the power connectorare arranged in a single terminal connector along a common strip.Further, the power module is adapted to connect to the power connectorin addition to the signal connector. Preferably, the electrical cabinetfurther comprises a user interface adapted to provide a status of eachuniversal bay indicative of the use of the universal bay. Additionally,each universal bay comprises a sensor circuit indicating to the userinterface the type of device positioned in the universal bay.

[0029] In an alternate embodiment of the present invention, a back panelfor use in an electrical cabinet of a modular uninterruptible powersupply (UPS) system is presented. The UPS is capable of including anycombination or exclusion of battery packs, power modules, and batterychargers within the capacity of the electrical cabinet, which has aplurality of identical receiving locations capable of receiving any oneof the power modules, battery packs, and battery chargers. In thisembodiment of the invention, the back panel comprises a backplane and afirst terminal connector. This terminal connector comprises a powerconnector mounted on the backplane and adapted to electrically connectwith the battery pack, the power module, and the battery charger. Theterminal connector also includes a signal connector mounted on thebackplane and adapted to electrically connect with the power module andthe battery charger.

[0030] In one embodiment of the back panel, the backplane comprises aprinted circuit board having power traces and signal traces includedtherein. These power traces and signal traces are operably coupled tothe power connector and the signal connector, respectively. Preferably,the back panel further comprises a second terminal connector positionedin a non-interfering relationship with the first terminal connector. Ina further embodiment, the back panel comprising a guide member rigidlymounted on the backplane. This guide member is adapted to receiveflanges on the battery packs, power modules, and battery chargers toensure proper positioning of the battery packs, power modules, andbattery chargers for engagement with the terminal connector.

[0031] In a further alternate embodiment of the present invention, anuninterruptible power system (UPS) comprises an electrical cabinethaving a plurality of universal receiving locations defined therein.These universal receiving locations are adapted to receive battery packsand power modules. The UPS further comprises a power module positionedwithin one of the universal receiving locations and a battery packpositioned within another one of the universal receiving locations.Preferably, the universal receiving locations are further adapted toreceive battery chargers, and the UPS further comprises a batterycharger positioned within a third of the universal receiving locations.Additionally, in one embodiment each of the universal receivinglocations comprises a terminal connector having a power connector and asignal connector positioned to electrically connect with both the powermodule and the battery pack upon insertion.

[0032] Other objectives and advantages of the invention will become moreapparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings incorporated in and forming a part ofthe specification illustrate several aspects of the present invention,and together with the description serve to explain the principles of theinvention. In the drawings:

[0034]FIG. 1 is an isometric view of an electrical cabinet or chassisfor configuring and supporting an UPS system, according to an embodimentof the present invention;

[0035]FIG. 2 is a front view of the electrical cabinet illustrated inFIG. 1;

[0036]FIG. 3 is an enlarged fragmentary view of a portion of FIG. 2;

[0037]FIG. 4 if an enlarged fragmentary view of a portion of FIG. 2;

[0038]FIGS. 5a and 5 b are rear isometric views of a power module foruse with the electrical cabinet illustrated in FIGS. 1-2;

[0039]FIGS. 6a and 6 b are rear isometric views of an individual batteryof a battery pack for use with the electrical cabinet illustrated inFIGS. 1-2;

[0040]FIG. 7 is a front view of the back panel used in the batterycabinet of FIG. 1;

[0041]FIG. 8 is a side view of the back panel of FIG. 7;

[0042]FIG. 9 is an isometric illustration of the back panel of FIG. 7;

[0043]FIG. 10 is a rear view of the back panel of FIG. 7;

[0044]FIG. 11 is an isometric view of an electrical cabinet or chassisfor configuring and supporting an UPS system similar to FIG. 1, but withthe side panels and back panel removed;

[0045]FIG. 12 is a simplified schematic diagram illustrating anembodiment of the battery center point sense circuitry in accordancewith an embodiment of the present invention;

[0046]FIG. 13 is an enlarged, partially fragmentary, isometric view ofan electrical cabinet according to an alternative embodiment of thepresent invention;

[0047]FIG. 14 is a isometric view of the rear end of a pair of batterypacks adapted to be plugged into the common strip terminal connector ofthe battery cabinet shown in FIG. 13; and

[0048]FIG. 15 is a isometric view of the rear end of a power moduleadapted to be plugged into the common strip terminal connector of thebattery cabinet shown in FIG. 13.

[0049] While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0050] For purposes of illustration, an embodiment of the presentinvention is depicted in FIGS. 1 and 2 as a modular chassis orelectrical cabinet 20 for supporting and organizing battery packs 22 andpower modules 24 into an uninterruptible power supply system (UPS) forsuch exemplary applications as providing power to computer networks,telecommunications equipment and any other application where anuninterrupted power source is desired. The cabinet 20 is also capable ofholding battery chargers 23 if desired, which are contained in the sametype of drawer support structure or module housing 25 as the powermodules 24 and plug into the back panel in a similar manner. The modulehousing 25 slides horizontally and locks into the inserted position.Further details of the module housing 25 and associated locking handlestructure are described in U.S. patent application Ser. No. 09/538,056entitled, “MULTI-FUNCTION HANDLE AND MODULAR CHASSIS INCORPORATINGSAME”, assigned to the present assignee, the entire disclosure of whichis hereby incorporated by reference.

[0051] As illustrated in FIGS. 1 and 2, the cabinet 20 is divided upinto individual sections 26 to provide a vertical stack. In thisembodiment, each section 26 provides three bays or slots 30 forreceiving the battery packs 22 or power modules 24. In this manner,electrical cabinets having only three slots, or alternatively six, nineor twelve or more slots can be readily made utilizing a single size ofside panels 38. It will be appreciated by those skilled in the art thateach section need only have one slot 30, but making each section withmultiple slots is advantageous from practicality and manufacturingstandpoints. Other slot configurations are also possible including sideby side horizontal slots as an alternative or in addition to thevertically spaced slots as shown. Each battery pack 22 is housedlaterally side by side in the illustrated embodiment such that eachbattery pack 22 may be inserted separately, which reduces the exertionof the service technician due to the typical heavy weight of suchbattery packs 22. Fewer or more battery packs may also be provided inother embodiments of the invention.

[0052] The power supply cabinet 20 may include a support base 32 uponwhich individual sections 26 can be stacked. The cabinet 20 alsoincludes an outer support housing which can be built out of variousmaterials such as plastic, sheet metal, metal, structural foam, andother similar materials. In the illustrated embodiment, the housingincludes a metal frame comprising vertical corner support bars 34 builtinitially on the support base 32. Referring to FIG. 11, adjacentvertical support bars 34 standing vertically upright from the cabinet 20are connected and spaced apart by a web 35 of sheet metal material nearthe top and bottom of the support bars 34. Pairs of vertical supportbars 34 are stamped and formed from a common sheet of metal. Thevertical corner support bars 34 are covered by a front panel (notshown), a back panel 40, and side panels 38. The vertical height of thesupport bars 34 is determined by the number of bays desired anddetermines the number of sections 26 provided, e.g. 3, 6, 9, or 12. Atop 42 that includes a user interface 43 including a display 45 extendsacross the top of the front panel, back panel 48 and side panel 38. Inthe illustrated embodiment the panels 38, 40 are formed of sheet metal,however other material may be used as previously indicated.

[0053] The side panels 38 and back panel 40 also include vents 44 forcooling purposes thereby preventing overheating of a UPS when in use. Inthe described embodiment and referring to FIG. 2, the vents 44 in theback panel 40 are all along the left hand side of the back panel 40 andrecessed a couple of inches rearward from an interior surface 49 toreceive rearwardly projecting fans 70 (FIG. 5a, 5 b) of the powermodules 24. In this manner, fans are positioned in close proximity withthe vents 44 to facilitate cooling of the power modules 24.

[0054] To provide the individual slots 30, individual shelves 28extending horizontally are supported in parallel, vertically spacedapart relationship. Like the side and back panels 38, 40, the shelves 28can be readily formed from sheet metal. The corners of the shelves 28are snapped in, mounted, fastened or otherwise secured to the verticalsupport bars 34. The shelves 28 also include generally flat andgenerally smooth top surfaces 46 which allows battery packs 23 or powermodules 24 to easily slide into and out of the slots 30. The uppersurface of the support base 32 can also provide the first shelf 33, i.e.the bottom surface of the lower most slot 30. A plastic center rail 47snaps into the center of each shelf 28 and extends rearwardly.Referring, also, now to FIG. 4, each center rail 47 provides beveledinner guide surfaces 51 that slide against corresponding inner beveledguide surfaces 55 of each battery pack 22 to align the battery packs 22in the proper position for plugging into their respective terminals.Referring, also, now to FIG. 3, the housing 25 of power modules andbattery chargers includes an elongate groove 29 that rides over the rail47. The shelf 28 above each slot 30 includes a downward depending flange57 on both side ends that provides parallel outer guide surfaces 59. Theouter guide surfaces 59 engage and slide against both the outer surfacesof the battery packs 22 and power modules 24 as shown in FIGS. 3 and 4to align the battery packs 22 and power modules 24 in the properposition for plugging into their respective terminals. Referring toFIGS. 6a and 6 b, the battery packs 22 also include a beveled surface 61that guides and eases insertion into the slots 30 against the outerguide surfaces 59.

[0055] In accordance with the present invention, the slots 30 areuniversal, readily capable of having either the power modules 24 or thetwo battery packs 22 inserted and plugged-in or otherwise electricallyconnected to the cabinet 20. In the described embodiment, differentterminal connector locations have been selected for the battery packs 22and the power modules 24 such that the locations of the respectiveterminals in each slot 30 do not interfere with one another. The batterypacks 22 are approximately one-half the width of the power modules 24.The power module 24 and the two side by side battery packs 22 are sizedclosely and just smaller than the size of the slots 30 such that theysubstantially fill the slot and substantially align to plug into therespective terminal connectors on the back 49 of each slot. Thus, it isnot only the cabinet 20 which is novel, but, also, the battery packs 22and power modules 24 that are also novel by virtue of their similarsizes and the selected non-interfering locations of the respectiveterminal connectors.

[0056] Referring to FIG. 3, it can be seen that the back 49 of each slot30 includes separate power module plug-in connectors 50 and batteryterminal plug-in connectors 52 at different locations. Each battery pack22 includes a positive and negative terminal 54, 56 in the form ofprojecting prongs or posts (FIGS. 6a and 6 b). Since, in the illustratedembodiment, each slot 30 may accommodate two battery packs 22, the back49 of each slot 30 includes two sets of battery terminal plug-inconnectors 52 in the form of positive and negative electrical sockets58, 60 positioned to align with positive and negative terminals 54, 56for interfitting and electrically connecting with the positive andnegative terminals 54, 56. Referring to FIG. 3, one of the batteryterminal plug-in connectors 52 is located proximate the horizontalcenter of the slot 30 while the other battery terminal plug-in connector52 is located proximate the right end of the slot 30. The plug-inconnectors for the battery packs 22 are known as power connectors asthey provide the raw power source or supply for the UPS system.

[0057] Similarly, the power module plug-in connectors 50 of the backpanel 40 are positioned to connect with corresponding plug-in connectors51 on the rear face of the power modules 24 (FIGS. 5a and 5 b). Thepower module plug-in connectors 50 are provided horizontally proximatethe bottom of the back surface 49 between the pair of battery terminalplug-in connectors 52. Each power module plug-in connector 50 includesmultiple pin sized sockets 62 for interfitting and electricallycontacting corresponding interfitting projecting pins 64 arranged inseparate terminal connectors 51 on the back surface of the power module24. The number of pins 64 allow for a variety of inputs, outputs andcontrol of the power module 24 or are otherwise necessary for carryinglarge quantities of electrical power. In particular, the single terminalconnector shown on the right hand side in FIG. 5a is a signal connector51 b and carries electronic control signals for controlling theoperational output of the power module 24. The signal connector 51 bplugs into a corresponding signal connector 50 b (see FIG. 7) on theback panel 40. In contrast, the four other terminal connectors 51 arepower connectors 51 a that receive the raw electrical power from thebattery packs 22 and also output conditioned power for use. The powerconnectors 51 a connect with corresponding power connectors 50 a on theinterior surface 49 of the back panel 40. The power module plug-inconnectors 50 and battery terminal plug-in connectors 52 also do notinterfere with the vents 44 and fans 70 which are aligned along the lefthand side.

[0058] The slots 30 are universal and each can receive either a powermodule 24 or a battery pack 22 as desired to better meet the poweringrequirements of a particular application. No changes need to be made tothe cabinet 20 to switch the number of power modules 24 or battery packs22 so long as the total does not exceed the numbered slots 30. The fillcapacity of the cabinet 20 can be utilized before another cabinet 20 isrequired. The end user is able to add additional battery packs 22 orpower modules 24 or switch locations of battery packs 22 and powermodules 24 as desired without concern as to whether a slot 30 isdedicated to receive either a battery pack or power module.

[0059] All of the plug-connectors 50, 52 are provided on a single backpanel 40 that provides an electrical circuit connecting the variousslots 30 in an operative manner. The back panel 40 of each section 26 isillustrated in FIG. 10 including a printed circuit board “back plane” inwhich traces 63 are etched on the back and front sides of a substrateboard 65. Traces 63 include signal traces 63 b and power traces 63 a.The narrower signal traces 63 b are electrically connected with socketsof signal connectors 50 b and carry electronic control signals to thepower modules 24. The wider power traces 63 a are electrically connectedwith sockets of the power connectors 50 a and carry the primaryelectrical power outputs of the battery packs 22 into the power modules24 and also output the conditioned electrical power for usage. It willbe appreciated by those skilled in the art that discrete wires may beused as an alternative to traces 63. The substrate board 65 supports theplug-in connectors 50 a-b, 52 on the interior side of the back panel 40as illustrated in FIGS. 7 and 9 (a side view of back panel 40 isillustrated in FIG. 8). The plug-in connectors 50 a-b, 52 areelectrically coupled to the traces 63 in an operative manner.

[0060] Guide mechanisms are also provided to precisely align therespective plug-in connectors of the battery packs 22 and the powermodules 24 with the back panel 40. The guide mechanism for guiding theconnection of the power modules 24 is illustrated in FIG. 5a and takesthe form of rearwardly-extending plastic flanges 66 on the power modules24 that co-act with corresponding structure on the back panel 40. Theplastic flanges 66 have beveled guide surfaces 67 that engage thecorners 69 (See FIG. 9) of receiving slots 71 defined on a plastic guidemember 73 of the back panel 40 which is rigidly mounted on an interiorfacing side of the substrate board 65. The beveled guide surfaces 67contact the corners 69 to adjust the position of the power module 24slightly to ensure that the pins 64 are properly received into thesockets 62.

[0061] As illustrated in FIGS. 6a and 6 b, the guide mechanism forguiding the connection of each battery pack 22 takes the form of anouter plastic guard 75 surrounding the positive and negative terminals54, 56 that co-acts with and fits over a corresponding plastic guard 77on the plastic guide member 73 of the back panel 40. The plastic guard77 on the plastic guide member 73 includes beveled guide surfaces 79that contact the corresponding guard 75 to adjust the position of thebattery pack 22 slightly to ensure that the positive and negativeterminals 54, 56 are properly received into the positive and negativesockets 58, 60.

[0062] The controller of the user interface 43 electronically polls eachbay or slot 30 to determine whether a battery pack 22, a power module 24or other device is provided in each of the slots 30. In the describedembodiment the controller 43 measures electrical activity, such as thelocation of the voltage in each slot 30. For example, if electricalactivity is sensed at the power module plug-in connectors 50 of aparticular slot 30, then the controller 43 determines that a powermodule 24 is present in that slot 30. Similarly, if electrical activityis sensed associated with the battery terminal plug-in connectors 52 ina particular slot 30, then the controller 43 determines that a batterymodule 22 is present in that slot 30. The controller 43 can also detectand indicate whether there are any defects of the power module 24 orbattery packs 22 by comparing sensed voltages or electrical signals tostored normal operating ranges, thereby providing an early warning to aUPS system maintenance technician. The polling is conducted at timedintervals such that the system automatically refreshes to reflect newinformation as power modules 24 or battery packs 22 are pulled orswitched. Other sensor mechanisms can also be used, such as usingindicator pins in the connectors to indicate a particular type ofplug-in module. Such information can be gathered with the controller 43and viewed on the display 45.

[0063] In one embodiment, a system for detecting defective battery packsin the modular, redundant uninterruptible power supply (UPS) systemutilizes a single analog sense input 80 into microcontroller 43 asillustrated in FIG. 12. One skilled in the art will recognize, however,that individual analog sense inputs may be used as desired. The senselines 82 a-c coupled to each of the battery center tap points on theback plane are selectively coupled to the single analog sense input 80to allow the microcontroller 43 to sequentially monitor the voltage ateach of these points. The selection circuitry in this embodimentincludes a shift register 84 that sequentially enables an electronicswitch, such as MOSFET 86 a-c to couple each of the sense lines 82 a-cto the single analog sense input 80. The shift register 84 operates incombination with a clock input 88 and a slot select input 90 frommicrocontroller 43. In this embodiment, a module send input 92 a-c isalso included to allow the microcontroller 43 to distinguish differenttypes of modules that may occupy the individual slots, as will bedescribed more fully below.

[0064] In the embodiment of the battery monitoring system of FIG. 12,the microcontroller 43 first establishes a baseline (all zeroes)position by clocking the shift register through its total cycle, e.g.,16 or more clock cycles for a typical shift register. Once this baselineall zeros position has been established, the microcontroller 43 sets theslot select line 90 high for one clock cycle. This causes shift register84 to enable the first switch 86 a to couple the sense line 82 a to theanalog sense input 80. The microcontroller 43 is then to sense thevoltage at the battery center tap for this slot. Once this reading hasbeen recorded, the slot select line 90 is taken low, and the shiftregister 84 is again clocked so that the next slot may be monitored whenthe slot select line 90 is again taken high. In this way, each of theindividual slots will be polled by the microcontroller 43 in thissequential fashion. At each clock, the voltage on analog sense inputwill indicate the condition of the battery center tap for each of thesubsequent slots.

[0065] As described above, the modular UPS chassis allows theinstallation of different types of modules therein. Specifically, eachslot may accommodate a pair of battery packs, or a power module orbattery charger. In a situation where a power module is installed in aslot, the voltage reading at the battery center tap sense line 82 forthat particular slot will read zero. To allow the microcontroller 43 todifferentiate this condition from a condition where batteries areinstalled but are inoperative, each slot also includes a module sendinput 92 a-c as introduced above. In one embodiment of the presentinvention, the power modules and battery chargers will output a squarewave on this module send line 92 to indicate their presence in the slot.During polling operation as the shift register 84 sequences to the slothaving the power module installed therein, when shift register 84enables the electronic switch, e.g., 8 a, the square wave on module sendline 92 a will result in the electronic switch 86 a being turned on andoff at the rate of the square wave. In this way, the microcontroller 43can detect that a power module is installed in that particular slot.

[0066] In a preferred embodiment, the square wave is generated at arelatively slow frequency, e.g., one-tenth the clock rate. Themicrocontroller 43 is then able to detect the square wave by virtue ofchanges from zero to 5 volts every 10^(th) cycle to thereby “decide”that a power module is installed in this location. As an alternative todetecting the presence of a module, an additional signal “module send”could be sent to the module. If a module is present in that location,the module will send a formatted CAN signal to the interconnect boardletting it know its system address. Interconnect board knows which slotthe module is in since it counts the number of clock pulses sent out. Ifat any given data shift there is no CAN message or insufficient DCvoltage is fed back, the system recognizes that the slot is empty.

[0067] Through the use of this system, the microcontroller 43 monitorsthe voltage at the center point of the two battery packs in eachindividual slot. As each pack is normally 60 volts in a typical UPSsystem, the nominal voltage at the battery center tap is 60 volts. Undernormal operating conditions, this point will always be about one-halfthe total string voltage. During float charge operation during which thecharge on each of the individual cells in the battery pack reachesapproximately 2.47 volts, the center point is then increased to anominal of approximately 74.1 volts (in a system having 30 cells perbattery pack). At a low battery discharge point during load each cellmay be reduced to approximately 1.75 volts, which therefore lowers thecenter point to approximately 52.5 volts under this operating condition.As these voltages are obviously greater than may be handled by a typicalmicrocontroller 43, the individual voltage sense from each slot isdivided down to a level safe for the microcontroller 43. In theembodiment illustrated in FIG. 12, the voltage input is scaled by one MΩand a 63.4 kΩ resistor, and clamped by a Zener diode to a safe level toprotect the microcontroller 43 from an overvoltage condition.

[0068] In operation, the microcontroller 43 polls each of the (3, 6, 9,or 12) slots in turn as discussed above. Initially, the microcontroller43 will “learn” each position's nominal voltage, which will varyslightly due to resistor and battery pack tolerances. Primarily, themicrocontroller 43 looks for consistency among the battery pairs in eachslot. If any single slot varies by more than a predetermined amount fromthe other slots, the microcontroller 43 will flag that slot as having aproblem. This consistency among the battery packs installed in the slotsis checked during each of the various operating conditions. Nominally,the microcontroller 43 expects to see a voltage of approximately 3.58volts in a quiescent state, 4.42 volts during a float charge mode, 3.13volts during low battery discharge under load, and 0.0 volts when nobatteries are installed in the slot. A typical variation in these valuesmay be limited to approximately 1% upon proper selection of sensingcomponents, although larger tolerance variations may be accommodated asneeded. A variation from these numbers by more than a predeterminedamount, e.g. by approximately 5% or more, will indicate that one or bothof the batteries in the slot has failed. The individual readings fromeach of the individual slots are compared against the nominal valuesexpected for each operating condition, and/or are compared against anaverage voltage value calculated from the voltage readings from all ofthe slots having batteries installed therein.

[0069] How the system reacts under different fault conditions allows themicrocontroller 43 to detect which battery pack in a particular slot isdefective. Recognizing that batteries typically fail high impedance(open cell, dry, or sulfated) different voltage readings duringparticular modes of operation may be used to identify which of the twobattery packs in a particular slot is failed. For example, themicrocontroller 43 will expect to see a nominal voltage during aquiescent mode of 3.58 volts when the “bottom” battery pack has failedopen. With this same failure, a voltage of 5.10 volts (corresponding tothe Zener clamping voltage) will be expected during the float chargemode of operation, and a voltage of 2.68 volts will be expected when thebottom battery pack is open during a low battery discharge under loadcondition. The “top” battery pack being failed open will result in anominal voltage of 3.58 volts to be seen by the microcontroller 43during all modes of operation. If both battery packs are failed open, orif no battery packs are properly installed in a particular slot, themicrocontroller 43 will expect to see a voltage of zero volts. With thisinformation, the microcontroller 43 can detect a defective battery bycomparing the sensed voltages at the battery center tap either againstthemselves or a known nominal value. In this way, the operationalreadiness or lack thereof of the battery packs installed in each slotsmay be indicated.

[0070] An alternative embodiment of the present invention is illustratedin FIGS. 13-15 as abattery cabinet 100 having a single strip terminalconnector 102 on a panel 103. Except for the configuration of the singlestrip terminal connector 102, the second embodiment is the same as thefirst embodiment. The single strip terminal connector 102 is adapted toplug into both battery packs 104 and power modules 106 and includes bothsignal connectors and power connectors. The power modules 106 includemetal prongs 108 and pins 109 that plug into prong receiving sockets 110and pin receiving sockets 111, respectively. The pins 109 act as signalconnectors and transmit electronic control signals while the prongs 108act as electrical power connectors and transmit the raw and/orconditioned electrical power. Each battery pack 104 also includes twoprongs 114 that plug into two of the same prong receiving sockets 110 asfor the power modules to provide the raw electrical power to the system.As such, two of the four prong receiving sockets 110 on each side of theterminal connector 102 are used for both battery packs and powermodules.

[0071] All of the references cited herein, including patents, patentapplications, and publications, are hereby incorporated in theirentireties by reference.

[0072] The foregoing description of various embodiments of the inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseembodiments disclosed. Numerous modifications or variations are possiblein light of the above teachings. The embodiments discussed were chosenand described to provide the best illustration of the principles of theinvention and its practical application to thereby enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

What is claimed is:
 1. A non-invasive method of monitoring operationalreadiness of electric power storage batteries in an uninterruptiblepower supply (UPS) system, the UPS system having at least one batterychannel, each having at least two battery packs coupled in series tosupply output power to a connected load and a battery charger tomaintain and restore charge to the batteries during normal utility lineoperation, comprising the steps of: monitoring a voltage at a midpointbetween the two battery packs during a quiescent state of operation ofthe battery packs; comparing the voltage to a first nominal value forthe midpoint voltage during the quiescent state of operation of thebattery packs; indicating a lack of operational readiness of bothbattery packs when the voltage at the midpoint is less than the firstnominal value by a first predetermined amount.
 2. The method of claim 1,wherein the UPS system includes a plurality of battery channels coupledin parallel with one another, and wherein the step of monitoringcomprises the step of monitoring a voltage for each of the parallelcoupled battery channels at a midpoint between the two battery packsduring a quiescent state of operation, the method further comprising thesteps of: calculating the first nominal value for the midpoint voltageduring the quiescent state of operation of the battery packs as theaverage of the voltages monitored for each parallel coupled batterychannel; and indicating a lack of operational readiness of a batterychannel when the voltage at the midpoint of the battery packs for thatchannel is less than the first nominal value by the first predeterminedamount.
 3. The method of claim 1, further comprising the steps of:monitoring the voltage at a midpoint between the two battery packsduring float charging of the battery packs; comparing the voltage to asecond nominal value for the midpoint voltage during the float chargingof the battery packs; indicating a lack of operational readiness of oneof the two battery packs when the voltage at the midpoint varies fromthe second nominal value by a second predetermined amount.
 4. The methodof claim 3, wherein the step of indicating a lack of operationalreadiness of one of the two battery packs comprises the step ofindicating a lack of operational readiness of a first one of the twobattery packs when the voltage at the midpoint is greater than thesecond nominal value by the second predetermined amount.
 5. The methodof claim 3, wherein the step of indicating a lack of operationalreadiness of one of the two battery packs comprises the step ofindicating a lack of operational readiness of a second one of the twobattery packs when the voltage at the midpoint is less than the secondnominal value by the second predetermined amount.
 6. The method of claim3, wherein the UPS system includes a plurality of battery channelscoupled in parallel with one another, and wherein the step of monitoringcomprises the step of monitoring a voltage for each of the parallelcoupled battery channels at a midpoint between the two battery packsduring the float charging, the method further comprising the steps of:calculating the second nominal value for the midpoint voltage during thefloat charging of the battery packs as the average of the voltagesmonitored for each parallel coupled battery channel; and indicating alack of operational readiness of a battery channel when the voltage atthe midpoint of the battery packs for that channel varies from thesecond nominal value by the second predetermined amount.
 7. The methodof claim 6, wherein the step of indicating a lack of operationalreadiness of a battery channel comprises the step of indicating a lackof operational readiness of a first one of the two battery packs of thatbattery channel when the voltage at the midpoint is greater than thesecond nominal value by the second predetermined amount.
 8. The methodof claim 3, wherein the step of indicating a lack of operationalreadiness of a battery channel comprises the step of indicating a lackof operational readiness of a second one of the two battery packs ofthat battery channel when the voltage at the midpoint is less than thesecond nominal value by the second predetermined amount.
 9. The methodof claim 1, further comprising the steps of: monitoring the voltage at amidpoint between the two battery packs at a state of discharge of thebattery packs; comparing the voltage to a third nominal value for themidpoint voltage during the state of discharge of the battery packs;indicating a lack of operational readiness of one of the two batterypacks when the voltage at the midpoint varies from the third nominalvalue by a third predetermined amount.
 10. The method of claim 9,wherein the step of indicating a lack of operational readiness of one ofthe two battery packs comprises the step of indicating a lack ofoperational readiness of a first one of the two battery packs when thevoltage at the midpoint is less than the third nominal value by thethird predetermined amount.
 11. The method of claim 9, wherein the stepof indicating a lack of operational readiness of one of the two batterypacks comprises the step of indicating a lack of operational readinessof a second one of the two battery packs when the voltage at themidpoint is greater than the third nominal value by the thirdpredetermined amount.
 12. The method of claim 9, wherein the UPS systemincludes a plurality of battery channels coupled in parallel with oneanother, and wherein the step of monitoring comprises the step ofmonitoring a voltage for each of the parallel coupled battery channelsat a midpoint between the two battery packs during the state ofdischarge, the method further comprising the steps of: calculating thethird nominal value for the midpoint voltage during the state ofdischarge of the battery packs as the average of the voltages monitoredfor each parallel coupled battery channel; and indicating a lack ofoperational readiness of a battery channel when the voltage at themidpoint of the battery packs for that channel varies from the thirdnominal value by the third predetermined amount.
 13. The method of claim12, wherein the step of indicating a lack of operational readiness of abattery channel comprises the step of indicating a lack of operationalreadiness of a first one of the two battery packs of that batterychannel when the voltage at the midpoint is less than the third nominalvalue by the third predetermined amount.
 14. The method of claim 12,wherein the step of indicating a lack of operational readiness of abattery channel comprises the step of indicating a lack of operationalreadiness of a second one of the two battery packs of that batterychannel when the voltage at the midpoint is greater than the thirdnominal value by the third predetermined amount.
 15. A method ofdetecting and identifying a failed battery pack in an uninterruptiblepower supply (UPS) system, the UPS system having a plurality of parallelconnected slots into which may be coupled battery packs, power modules,or battery chargers as determined and configured by a user, the slotsbeing adapted to accommodate two battery packs and providing a seriescoupling therebetween, the method comprising the steps of: detecting apresence and type of equipment installed in each slot; monitoring avoltage present at the series coupling between the two battery packs foreach slot into which is installed battery packs; calculating an averagemidpoint voltage for all slots having battery packs installed therein;comparing the voltage for each slot to the average midpoint voltage forall slots; and identifying a failed battery pack within a slot when thevoltage for its associated slot deviates from the average midpointvoltage by a predetermined amount.
 16. The method of claim 15, furthercomprising the steps of: comparing the voltage for each slot to apredetermined expected value; and identifying a failed battery packwithin a slot when the voltage for its associated slot deviates from thepredetermined expected value by a predetermined amount.
 17. The methodof claim 16, further comprising the step of determining an operatingmode of the battery packs, and wherein the step of comparing the voltagefor each slot to a predetermined expected value comprises the step ofcomparing the voltage for each slot to an operating mode specificpredetermined expected value, and wherein the step of identifying afailed battery pack within a slot when the voltage for its associatedslot deviates from the predetermined expected value by a predeterminedamount comprises the step of identifying a failed battery pack within aslot when the voltage for its associated slot deviates from theoperating mode specific predetermined expected value by a predeterminedamount.
 18. The method of claim 17, wherein the step of determining anoperating mode of the battery packs determines that the battery packsare operating in a quiescent mode, and wherein the step of identifying afailed battery pack within a slot comprises the step of identifying bothbattery packs as failed when the voltage for their associated slot isless than a first predetermined value by a first predetermined amount.19. The method of claim 17, wherein the step of determining an operatingmode of the battery packs determines that the battery packs areoperating in a float charging mode, and wherein the step of identifyinga failed battery pack within a slot comprises the step of identifying afirst one of the two battery packs within the slot as failed when thevoltage for its associated slot is less than a second predeterminedvalue by a second predetermined amount, and identifying a second one ofthe two battery packs within the slot as failed when the voltage for itsassociated slot is greater than a third predetermined value by a thirdpredetermined amount.
 20. The method of claim 17, wherein the step ofdetermining an operating mode of the battery packs determines that thebattery packs are operating in a discharging mode, and wherein the stepof identifying a failed battery pack within a slot comprises the step ofidentifying a first one of the two battery packs within the slot asfailed when the voltage for its associated slot is less than a fourthpredetermined value by a fourth predetermined amount, and identifying asecond one of the two battery packs within the slot as failed when thevoltage for its associated slot is greater than a fifth predeterminedvalue by a fifth predetermined amount.
 21. The method of claim 15,wherein the step of detecting a presence and type of equipment installedin each slot comprises the step of polling each slot for an equipmenttype identifier.
 22. A system for detecting defective battery packs in amodular, redundant uninterruptible power supply (UPS) system, the UPSsystem having a plurality of parallel connected slots into which may becoupled the battery packs, power modules, or battery chargers asdetermined and configured by a user, each slot being adapted toaccommodate two battery packs and to provide a series couplingtherebetween, the system comprising: a voltage sense circuit coupled toeach series coupling of each slot and operable to generate a voltagesense signal in response to a voltage present thereon; a voltage senseselector circuit coupled to each of the voltage sense circuits, thevoltage sense selector circuit operable to selectively enable thevoltage sense circuits; a controller operably coupled to the voltagesense selector circuit to command the voltage sense selector circuit toenable of a particular voltage sense circuit for a particular slot, thecontroller reading the voltage sense signal for the particular slot fromthe voltage sense circuit; and wherein said controller compares thevoltage sense signal for the particular slot to a predetermined expectedvalue and identifies an operational status of the battery packs basedthereon.
 23. The system of claim 22, wherein the controller reads thevoltage sense signal for each slot in which battery packs are installed,calculates an average voltage value, and compares the voltage sensesignal for each slot to the average voltage value to identify theoperational status of the battery packs for each slot.
 24. The system ofclaim 23, wherein the controller reads the voltage sense signal for eachslot in which battery packs are installed during a float charge mode,compares the voltage sense signal for each slot to an expected voltagevalue for the float charge mode, and identifies a first one of thebattery packs in a slot as defective when the voltage sense signal forthe associated slot is less than the expected voltage value for thefloat charge mode, and identifies a second one of the battery packs in aslot as defective when the voltage sense signal for the associated slotis greater than the expected voltage value for the float charge mode.25. The system of claim 23, wherein the controller reads the voltagesense signal for each slot in which battery packs are installed during adischarge mode, compares the voltage sense signal for each slot to anexpected voltage value for the discharge mode, and identifies a firstone of the battery packs in a slot as defective when the voltage sensesignal for the associated slot is less than the expected voltage valuefor the discharge mode, and identifies a second one of the battery packsin a slot as defective when the voltage sense signal for the associatedslot is greater than the expected voltage value for the discharge mode.26. The system of claim 22, wherein the voltage sense selector circuitcomprises a shift register having a clock input and a slot select inputfrom the controller, the shift register sequentially generating aplurality of output enable signals in response to the clock input andthe slot select input from the controller, each of the output enablesignals operative to turn on a switching element to connect the voltagesense circuit to the controller.
 27. The system of claim 26, wherein theswitching element is a metal oxide silicon field effect transistor(MOSFET).
 28. An electrical cabinet for configuring an uninterruptiblepower system, the cabinet comprising a plurality of receiving locationseach adapted to receive either of a power module and a battery pack,each receiving location including at least one terminal connectorcomprising a first power connector adapted to electrically connect withthe battery pack and a signal connector adapted to electrically connectwith the power module.
 29. The electrical cabinet of claim 28, whereineach receiving location includes a first terminal connector and aseparate second terminal connector arranged in non-interferinglocations.
 30. The electrical cabinet of claim 28 wherein the signalconnector and the power connector are arranged in a single terminalconnector along a common strip.
 31. The electrical cabinet of claim 30wherein the power modules are adapted to connect to the power connectorin addition to the signal connector.
 32. The electrical cabinet of claim28 further comprising partitions dividing the receiving locations intoslots.
 33. The electrical cabinet of claim 28 further comprising a userinterface adapted to provide a status of each receiving location that isindicative of the use of the receiving location.
 34. The electricalcabinet of claim 33 wherein each receiving location comprises sensingmeans indicating to the user interface the type of device positioned inthe receiving location.
 35. The electrical cabinet of claim 28 whereineach receiving location is adapted to receive at least two batterypacks, and wherein each said receiving location includes a pair of saidfirst terminal connectors, one first terminal connector for eachdifferent battery pack.
 36. The electrical cabinet of claim 28 whereineach power module includes a fan, each receiving location including avent arranged to be in close proximity to the fan of a power modulepositioned therein.
 37. The electrical cabinet of claim 28, furthercomprising: a support base; support bars spaced apart in rectangularrelationship extending vertically and parallel from the support base;side panels extending vertically and generally parallel betweendifferent pairs of the four support posts; and a plurality of shelvesextending horizontally between the four support posts in spaced apartparallel relationship, the receiving locations being defined betweenadjacent shelves; and a back panel associated with the receivinglocation, the back panel extending generally perpendicular to theshelves and transversely between the side panels and two of the supportbars, the back panel supporting the at least one terminal connector. 38.The electrical cabinet of claim 37 wherein the shelves, the side panels,and the support bars are manufactured from sheet metal material, pairsof the support bars being connected and maintained in spaced relation bya web of sheet metal material.
 39. The electrical cabinet of claim 28,wherein said plurality of receiving locations are also adapted toreceive a battery charger, and wherein said first power connector andsaid signal connector are adapted to electrically connect with thebattery charger.
 40. An electrical cabinet for configuring anuninterruptible power system with battery packs and modules, comprising:a support housing; a plurality of universal bays defined in the supporthousing, each universal bay sized to receive either of a battery packand a power module; and at least one terminal connector for eachuniversal bay, comprising a first power connector adapted toelectrically connect with the battery pack and a signal connectoradapted to electrically connect with the power module.
 41. Theelectrical cabinet of claim 40, wherein each universal bay includes afirst terminal connector and a separate second terminal connectorarranged in non-interfering locations.
 42. The electrical cabinet ofclaim 41 wherein the housing defines a guide surface for each universalbay adapted to guide the battery pack into electrical connection withthe first power connector and guide the power module into electricalconnection with the signal connector.
 43. The electrical cabinet ofclaim 42 wherein each of the signal and power connectors include a guidemechanism which interacts with a corresponding guide mechanism on eitherof the battery pack and power module, wherein the guide surface isadapted to first locate the corresponding guide mechanisms forinteraction, and then the respective corresponding guide mechanismsguide the battery packs and power modules into electrical connectionwith the power connectors and signal connectors, respectively.
 44. Theelectrical cabinet of claim 40 wherein the signal connector and thepower connector are arranged in a single terminal connector along acommon strip.
 45. The electrical cabinet of claim 44 wherein the powermodule is adapted to connect to the power connector in addition to thesignal connector.
 46. The electrical cabinet of claim 40 furthercomprising a user interface adapted to provide a status of eachuniversal bay that is indicative of the use of the universal bay. 47.The electrical cabinet of claim 46 wherein each universal bay comprisesa sensor means indicating to the user interface the type of devicepositioned in the universal bay.
 48. The electrical cabinet of claim 40,wherein the support housing comprises: a support base; support barsspaced apart in rectangular relationship extending vertically andparallel from the support base; side panels extending vertically andgenerally parallel between different pairs of the four support posts;and a plurality of shelves extending horizontally between the foursupport posts in spaced apart parallel relationship, the universal baysbeing defined between adjacent shelves; and a back panel associated withthe universal bays, the back panel extending generally perpendicular tothe shelves and transversely between the side panels and two of thesupport bars, the back panel supporting the at least one terminalconnector.
 49. The electrical cabinet of claim 48 wherein the shelves,the side panels, and the support bars are manufactured from sheet metalmaterial, pairs of the support bars being connected and maintained inspaced relation by a web of sheet metal material.
 50. The electricalcabinet of claim 49 wherein the back panel comprises a printed circuitboard backplane.
 51. The electrical cabinet of claim 40 wherein eachbattery pack is dimensioned to be about one half the size of a powermodule, such that each universal bay is adapted to receive either of twobattery packs side by side and a power module.
 52. The electricalcabinet of claim 40, wherein each universal bay is sized to additionallyreceive a battery charger, and wherein said at least one terminalconnector for each universal bay is adapted to electrically connect tosaid battery charger.
 53. A back panel for use in an electrical cabinetof a modular uninterruptible power supply (UPS) system, the UPS beingcapable of including any combination or exclusion of battery packs,power modules, and battery chargers within the capacity of theelectrical cabinet, the electrical cabinet having a plurality ofidentical receiving locations capable of receiving any one of the powermodules, battery packs, and battery chargers, the back panel comprising:a backplane; and a first terminal connector, said terminal connectorcomprising: a power connector mounted on said backplane and adapted toelectrically connect with the battery pack, the power module, and thebattery charger; and a signal connector mounted on said backplane andadapted to electrically connect with the power module and the batterycharger.
 54. The back panel of claim 53, wherein said backplanecomprises a printed circuit board having power traces and signal tracesincluded therein said power traces and signal traces being operablycoupled to said power connector and said signal connector, respectively.55. The back panel of claim 53, further comprising a second terminalconnector positioned in a non-interfering relationship with said firstterminal connector.
 56. The back panel of claim 53, further comprising aguide member rigidly mounted on said backplane, said guide memberadapted to receive flanges on the battery packs, power modules, andbattery chargers to ensure proper positioning of the battery packs,power modules, and battery chargers for engagement with the terminalconnector.
 57. An uninterruptible power system (UPS), comprising: anelectrical cabinet having a plurality of universal receiving locationsdefined therein, said universal receiving locations being adapted toreceive battery packs and power modules; a power module positionedwithin one of said universal receiving locations; and a battery packpositioned within another one of said universal receiving locations. 57.The UPS of claim 57, wherein said universal receiving locations arefurther adapted to receive battery chargers, the UPS further comprisinga battery charger positioned within a third of said universal receivinglocations.
 58. The UPS of claim 57, wherein each of said universalreceiving locations comprises a terminal connector having a powerconnector and a signal connector positioned to electrically connect withboth the power module and the battery pack upon insertion thereof.